The present invention relates to a process and an apparatus for continuously conveying particulate material under pressure, and more particularly for conveying coal dust to a combustion or gasification chamber.
In the prior art, it is known to pressurize particulate material, such as coal dust, by using pressure compartments, commonly known as pressure locks. Such pressure compartments subject the coal dust to pressure above atmospheric pressure and thereby cause portions of the coal dust to agglomerate, that is to form lumps.
It is further known to mix the coal dust with fluids, such as water or oil, and pump the resulting mixture to a combustion chamber using pressure sludge pumps. This approach also compacts the particulate material into lumps, thus making the continuous conveying of the particulate material both difficult and unreliable.
Furthermore, the water or oil component of the pumped mixture causes other difficulties, because the coal dust is not sufficiently wettable, as well as being an undesired additive, especially in applications where the particulate material is to be employed in a combustion or gasification chamber.